This invention relates to the measurement of small hair-like particles in a fluid, such as measurement of the amount of asbestos fiber in air. Asbestos fiber is in the order of 1/10 micron in diameter and of highly variable length, with the length always much greater than the diameter. It has been noted that the presence of asbestos fiber in air has an adverse affect on the health of people breathing the air and therefore simple and reliable equipment for measuring the amount of such fiber in air is desirable.
Accordingly, it is an object of the present invention to provide a new and improved apparatus for measuring hair-like particles in fluid, such as asbestos fiber in air, and to distinguish such hair-like particles from other geometrically different particles.